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Don't bump the next_node_counter when using a removed counter #3367

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Merged
merged 1 commit into from
Oct 29, 2024
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Don't bump the next_node_counter when using a removed counter #3367

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6 changes: 3 additions & 3 deletions lightning/src/routing/gossip.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2077,9 +2077,9 @@ where
},
IndexedMapEntry::Vacant(node_entry) => {
let mut removed_node_counters = self.removed_node_counters.lock().unwrap();
**chan_info_node_counter = removed_node_counters
.pop()
.unwrap_or(self.next_node_counter.fetch_add(1, Ordering::Relaxed) as u32);
**chan_info_node_counter = removed_node_counters.pop().unwrap_or_else(|| {
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Could we add a call to test_node_counter_consistency to the end of this method? From local testing it looks like this would've caught the bug. Not sure if other methods could use it as well.

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We don't appear to have any test coverage which removes then adds a channel, so even with a new check in this method none of our tests fail. Ultimately we end up panicing immediately when the next message comes in, though, so running a real node with debug assertions on hit this pretty quick :)

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@valentinewallace valentinewallace Oct 29, 2024 •
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FWIW, I get two test failures with this diff (i.e. reverting the fix and adding the check):

diff --git a/lightning/src/routing/gossip.rs b/lightning/src/routing/gossip.rs
index 9d85a6c58..f761e6a63 100644
--- a/lightning/src/routing/gossip.rs
+++ b/lightning/src/routing/gossip.rs
@@ -2077,9 +2077,9 @@ where
                                },
                                IndexedMapEntry::Vacant(node_entry) => {
                                        let mut removed_node_counters = self.removed_node_counters.lock().unwrap();
-                                       **chan_info_node_counter = removed_node_counters.pop().unwrap_or_else(|| {
+                                       **chan_info_node_counter = removed_node_counters.pop().unwrap_or(
                                                self.next_node_counter.fetch_add(1, Ordering::Relaxed) as u32
-                                       });
+                                       );
                                        node_entry.insert(NodeInfo {
                                                channels: vec![short_channel_id],
                                                announcement_info: None,
@@ -2088,6 +2088,9 @@ where
                                },
                        };
                }
+               core::mem::drop(channels);
+               core::mem::drop(nodes);
+               self.test_node_counter_consistency();

                Ok(())
        }

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Lol, I'm an idiot, I ran the test without reverting the diff. I'll add this in a followup, anyway.

self.next_node_counter.fetch_add(1, Ordering::Relaxed) as u32
});
node_entry.insert(NodeInfo {
channels: vec![short_channel_id],
announcement_info: None,
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